Color-screen.



H. E. MERWIN.'

GOLOB. SCREEN.

APPLIOATION FILED ma. za, 1910.

977,420. Patented N0v.29, 1910.

2. 2| lu@ Q I lu@ l vz'let B Ime/wao@ HERBERT E. MERWIN, 0F HENSONVILLE,NEW YORK.

COLOR-SCREEN.

Specieation of Letteral Patent.

Patented Nov. 29, 1910.

Application led March 23, 1910. Serial No. 551,127.

To all whom 'it may concern:

Be it known that I, HERBERT E. MERWIN, of Hensonville, in the county ofGreene and State of New York, have invented certain new and usefulImprovements yin Color- Screens; and I hereby xdeclare that thefollowingis a full, Clear, and exact description thereof, reference being had tothe accompanying drawings, which form part of this specification.

This invention is a color screen to be used for detecting anddetermining whether certain chemical elements or compounds are containedin various substances, by noting the effect that such chemicalsubstances have on the color of a flame-(usually that of a Bunsenburner)-as seen through the screen when such a substance is introducedinto such ame and burned or heated thereby.

The screen consists essentially of three parallel differently-coloredbars or strips of transparent or translucent material, (preferablyCelluloid), one of which bars has an absorption spectrum like methylviolet; another like anilin blue; and the third bar combines both theblue and the violet. The screen is preferably formed of two sheets oftransparent Celluloid which are partially overlapped, and one sheet isVstained with organic dyes so as to give an absorption spectrum likemethyl violet and the other stained to give an absorption spectrum likeanilin blue, the outer portion of each sheet forms one bar of the screenand the overlapped portion of the two sheets forms the third bar of thescreen and combines the two colors. Such a screen will absorb the orangeand yellow of the spectrum; the blue bar of the screen absorbs stronglyfrom about 23 (in the spectrum scale having D at 50) to 60; that is,including the orange-red, the orange and half the yellow; the violet barof such screen absorbs strongly from about 33 to 70; that is, the orangeand the yellow; the sodium line at 50 is therefore absorbed by bothbars. Thus rin the presence of sodium the red, green and blue colors imarted to the llame by certain elements and) compounds may be readilydetected by means of the screen. Certain colors transmitted by one barare absorbed by the central bar of the screen.

v In the accompanying drawings-Figure 1 illustrates the preferredconstruction of such a screen;` and Fig. 2 1s an enlarged sectlonthereof on line 2 2, Fig. 1.

The screen, as shown in Figs. 1 and 2, consists of a sheet A, oftransparent material, preferably Celluloid, stained blue, and a sheet Bof like material stained violet, and these sheets are overlappedlongitudinally, as at C, so that the complete screen presents alongitudinal bar a of blue; a similar bar I) of violet, and anintermediate bar c which combines -both the blue. and violet. The sheetsA and B may be secured together in any suitable manner, so that thescreen can be handled as a unit. If the sheets are of Celluloid Ipreferably use a cement formed by dissolving Celluloid in a suitablesolvent, as such Cement will not affect the colors of the screen. WhileI prefer to use Celluloid, other solid transparent material stained andoverlapped as shown can be used; but it is practically impossible toproduce 'the desired colors in glass, because suitable coloring matterswill decompose at the temperature required to make glass.

The essential feature of the screen consists in sheets of suitabletranslucent or transparent material stained as described, with organictints or Colors, so'as to give three distinct bars each' having a deepabsorption spectrum.

A screen about 3 X 5 inches in size and having three colored bars, oneblue, one violet, and one combining the blue and violet, is bestsuitable for general laboratory use. Such a screen can Abe convenientlyhandled and is a most delicate but' certain means of identifying theChemicalV elements usually sought by means of the spectroscope, and itsuse greatly facilitates the work of laboratory instruction inqualitative analysis and mineralogy.

In obtaining flame react-ions from nonvolatile Compounds some flux oracid should be used that will produce a volatile compound ofv theelement sought. For example a silicate containing potassium may bepowdered, and decomposed in asodium carbonate bead on a platinum wire;the resulting potassium carbonate is volatile. The phosphate minerals,apatite, lazulite and wavellite, give the phosphoric acid reactionreadily 1f powdered, taken up on a moistened loop of platinum wire,heated and 'then treated with concentrated sulfuric acid and againheated. The reaction is transient.

Viewed through the screen, strontium and lithium llames appear deep redthrough the violet bar, but givcno color through the blue bar. Bariumand boron give a vivid green through the blue bar, and only a faintgreen through the violet bar. Volatile calcium salts impart a stronggreenish-yellow color to the flame as seen through the blue bar, butthrough the violet bar the color appears a pale red. Through thecombination-bar the flame has a tino'e of green. The color flashes outonly at the moment when the salt is becoming incandescent. Potassiumseen through the blue bar has an intense blue-violet color; through theviolet bar the outside of the Bunsen flame is violet and the insideviolet-red; through the combination-bar the flame appears as through theviolet screen, but less bright, and with red predominating. These colorsare very characteristic. The copper chlorid flame appears bright bluefrlnged with green through the violet bar; brilliant green through theblue bar, and a paler reen through the combination-bar. The ame color ofphosphoric acid is green through the blue bar, light rose color(Violet-red) through the violet bar and pale green through thecombination-bar.

In case lithium light free from sodium light is wanted for use inoptical mincralogy the violet bar is a very serviceable filter.

What I claim is:

l. A color screen comprising two sheets of suitable material, and ofdifferent organic color, overla ped to form an intermediate barcontaining both colors; substantially as set forth.

2. A color screen for the purpose specified comprising two sheets ofsuitable material, one violet and the other blue overlapped to form anintermediate bar combining both colors; substantially as described.

3. A llame color screen formed of two transparent Celluloid sheets, onestained methyl violet and the other anilin blue, said sheets beingpartially overlapped to form a bar containing both colors; substantiallyas and for the purpose set forth.

In testimony that I claim the foregoing as my own, I atliX my signaturein presence of two Witnesses.

H. E. MERWIN.

Witnesses:

G. A. RANKIN, FRED E. WRIGHT.

